<mat-card>
  <h3 class="title">简单的转场动画 <span>openClosed</span></h3>
  <button mat-raised-button (click)="toggle()">{{isOpen?'closed':'open'}}</button>
  <div [@openClose]="isOpen ? 'open' : 'closed'" class="open-close-container">
    <p>The box is now {{ isOpen ? 'Open' : 'Closed' }}!</p>
  </div>
</mat-card>
